Formation and degradation of deamido-TRH (pyroglutamyl-histidyl-proline) in rat brain after intraventricular injection of TRH.
Thyrotropin-releasing hormone (TRH) injected into the lateral ventricle of the rat's brain was rapidly metabolized to deamido-TRH (DA-TRH). Brain levels of TRH decreased with a half-life of 7 min, while the DA-TRH formed from its disappeared with a half-life of 2.5 min. To prevent the post-mortem degradation of DA-TRH it was necessary to sacrifice rats by directing focused microwave irradiation towards the brain. The short half-lives determined for TRH and DA-TRH in vivo were much shorter than those obtained using in vitro techniques. The in vivo formation and accumulation of DA-TRH was inhibited by bacitracin and unaffected by probenicid.
D000818:Animals; D001414:Bacitracin / Q000494:pharmacology; D001921:Brain / Q000378:metabolism*; D006207:Half-Life; D007276:Injections, Intraventricular; D007700:Kinetics; D008297:Male; D011339:Probenecid / Q000494:pharmacology; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism*
D001414:Bacitracin; C020271:thyrotropin-releasing hormone, deamido-; D013973:Thyrotropin-Releasing Hormone; D011339:Probenecid; D011761:Pyrrolidonecarboxylic Acid